The present invention relates generally to techniques for long term data archiving in a storage system. More particularly the present invention relates to a file server or network attached storage (NAS) system and method for implementing long term data archiving.
Conventionally, long term data archiving has been accomplished using write once read many (WORM) storage media. Recently the need for long term data archiving has increased. This need has been made more acute, for example, by the passage of various regulations. These regulations include, for example, Regulations like SEC (Securities and Exchange Act) and 21 CFR (Code of Federal Regulations) Part 11 of the Food and Drug Administration (FDA) act. These regulations require regulated companies to protect regulated data and to retain the regulated data for long periods, such as, 7 years in the case of SEC regulations. Regulations in some industries don't allow people to modify any stored data if the data is in fact regulated data. Another important factor in such regulations is the requirement that the data be allowed to be modified during the retention period.
Traditional file servers or NAS appliances don't meet the above described regulations. File servers or NAS appliances or file systems in operating systems are commonly used for storing files into storage medium. Hard disk drives have been and are being used as such storage medium. As is well known data stored on hard disk drives can be easily modified. Thus, hard disk drives do not in and of themselves meet the above described regulations.
Conventional NAS and Content Addressed Storage (CAS) provide WORM capability. However, conventional NAS and CAS products that provide this capability do not allow any modification of data stored once it has been stored therein.
For example, the NAS Filer products of Network Appliance, Inc. provide what is described as a SnapLock (Trademark of Network Appliance Inc.) function. “SnapLock Compliance and SnapLock Enterprise Software”, Network Appliance, Inc. 2003. This function allows a user to specify a file that needs to be protected and a retention period for the file. After a WORM bit has been set for a specified file by applications, the Filer does not allow any user to modify or delete the specified file until the retention period has expired.
As described above there is a requirement to allow for the modification of a protected file during a retention period. To accomplish such according to the NAS SnapLock function, a user is required to copy the file to another volume or filer and then protect the copied file using the SnapLock function. This allows the original file to be modified. However, this procedure requires several steps and as such is inconvenient to the user particularly which numerous file are involved.
Further, for example, the CAS Centera (Trademark of EMC Corporation) products of EMC Corporation provide a specialized storage to store fixed contents. “Centera Content Addressed Storage: Product Description Guide”, EMC Corporation 2003. Once data has been stored in a Centera storage, the Centera storage does not allow users to modify or delete the data until the specified retention period has expired. There is no way to modify the stored data.
The same as NAS, there is a requirement to allow for the modification of a protected file during a retention period. To accomplish such according to the CAS Centera storage, a modified file is stored as a different file with a different ID. The CAS Centera storage also stores the original file. However, as per the CAS Centera storage the user is required to manage both files and IDs. This additional task represents an inconvenience to the user.